This invention relates to vehicle safety devices. It is primarily concerned with safety of persons in automobiles and other vehicles resulting from a collision.
Various vehicle safety devices have been proposed including those dependent on inertia and those with power drive or power assist. Inertia type devices are responsive to inertial forces. Motions that can be produced by external power are generally believed unachievable by inertia responsive devices. The inertia type can be typified by U.S. Pat. Nos. 2,818,900 to Burnett, 3,452,543 to Zellar, and 2,823,730 to Lawrence. Power-operated devices use externally generated power to force a particular motion or motions. Power operated safety devices are typified by U.S. Pat. Nos. to Calandra 3,858,930, Racine 2,970,862, and Krous 3,789,650.
It is an object of the present invention to provide movement of a vehicle seat in such fashion as to increase or take advantage of the factors that are involved in retaining a human body in the seat of the vehicle involved in a collision. These factors include time or duration of movement of the seat, distance moved, and pressure applied by the seat to the occupant. There is a very short duration, on the order of 0.03 seconds depending upon vehicle speed at impact, between the instant an occupant's forward momentum starts propelling him forward to the instant when the occupant has impacted the windshield and flown through it or has impacted an immovable barrier within the vehicle. A device designed to prevent such injury impacts must function within that very short duration.
Power operated safety devices have serious disadvantages. They require that a sensor respond to an event and initiate an action or that some other mechanism perform a function to cause the device to work. Such requirements require precise timing and can fail to perform within the time duration available or at least can fail to perform soon enough for the device to do its job within that duration. Also, power operated safety devices are very expensive and have a number of components that can deteriorate or fail. To the contrary, upon vehicle impact, the present device responds entirely to the inertia of the vehicle seat, and seat back, if connected to the seat, to initiate its action. In other words, the device functions instantly in response to the shock force of a collision. The present device is inexpensive and has only a few parts.
The instant safety device utilizes a perceived difference between the inertial reaction of the inanimate seat and seat back to a collision and the inertial reaction of a live occupant. In this respect, it appears that the inanimate seat and seat back react and move more quickly than does the live passenger. The safety device produces a motion to the seat that dissipates the forward momentum of the passenger by moving the passenger upward as well as forward to increase both the distance and duration of travel of the occupant. The result is that the passenger remains bonded to the seat longer, beyond the time his momentum would have propelled him from the seat. In addition, spinal compression is minimized by the device of this invention. The device dissipates momentum and stops all parts of the passenger's body, not just some. For example, there is minimum head snap or whiplash with this device.
It has been determined that if the seat is mounted so that the rear of the seat and the front of the seat will move forward and upward, but at different rates, the factors above mentioned will be improved and the person riding on the seat will be retained on the seat without injury from the collision. One of the effects of the upward movement of the seat is that, since the live occupant does not move as quickly as the inanimate seat, the upward movement of the seat applies increased pressure force to the bottom of the occupant and increases the frictional contact between the occupant and the seat. This increased friction further helps in maintaining contact between the occupant and the seat. In other words, the bonding force between the seat and the occupant is increased because the seat, both at its front and rear, moves upwardly faster than does the live passenger.
It has been determined that the action required of the device when connected to a seat, typically the front seat, to which a seat back is integrally connected, is different from the action required when the device is connected to a seat, typically the back seat, to which no seat back is connected. (The seat back is connected directly to the chassis.) For this reason, one embodiment, the first described, although usable on a front seat, is better suited for installation with a seat to which no back is connected, typically a rear seat. The remaining embodiments of the device are better suited for installation on a seat that has a seat back connected to it, typically a front seat. However, these remaining embodiments can be used on a backless seat. The differences between these embodiments will be described.
First, however, common to all embodiments is the fact that in a conventional vehicle, the connections between the seat frame and the floor frame may be by a fixed mounting means such as bolts or welding, or may be by slidable mounting means that enable adjustment of the seat such as to accommodate the driver of the vehicle. In the present invention, the seat frame and floor frame are constructed to accommodate the devices of the embodiments of this invention. In each of the first two embodiments, there are two links connected between the floor frame and the seat frame. The two links are of different lengths, the rear link being short and the front link being long. In the initial rest or unactivated condition, the forward ends of the links are pivotally connected to the floor frame while the rearward ends are pivotally connected to the seat frame. Thus, for the seat frame (and the seat) to move forward, it is forced by the links to move upward also. The rear link being shorter than the front link, any forward movement of the seat will pivot the rear link through a relatively greater arc while the longer forward link swings through a smaller arc, resulting in a greater lift rate of the front of the seat relative to a smaller lift rate of the rear.
It has been found that with a normal pitch of the seat itself from front to rear and with a seat of normal weight, the initial movement which brings the small rear link toward a vertical position, is sufficient to absorb the energy and stop the forward movement of the body of the occupant. However, because of an extremely high speed impact, the rear pivot may swing past 90.degree., thus raising the forward rocking part of the seat even further, while lowering the rear back to or toward the original elevation thereby applying increased rearward resistance to forward movement of the occupant.
In a third embodiment of the invention, the means for controlling movement of the seat comprises a link with pivotal connections between the floor and seat frames and a pin and slot connection between those frames. The pin and slot are at the rear of the seat and the link is at the front. Preferably, the pin is affixed to the seat frame and the slot is in the floor frame. The slot is located and oriented relative to the seat to cause the pin, and therefore the rear of the seat, to rise at about a 30.degree. angle to a horizontal plane as the seat propels forward. As the front link swings about its pivotal connection to the floor frame, its point of connection to the seat frame traces an arcuate path. However, the length of the link and the locations of its end connections cause the average angle of this arc to approximate about a 45.degree. angle relative to a horizontal plane.
A seat back connected to the back of a seat can affect the operation of the safety device. The seat back acts as a moment arm that adds to the weight of the seat and the occupant in applying a downward force at the front of the seat. To deal with this effect, a fourth embodiment retains the rear connection formed by a pin in approximately a 30.degree. slot, but the forward connection comprises a dual component link. The first link component has a forward end pivotally connected to the floor frame and its rearward end is pivotally connected to the forward end of a second link component. The rearward end of the second link component is pivotally connected to the seat frame. In the at-rest and during initial or first stage movement of the device, the upper surface of the second link bears against a bearing surface on the seat frame, causing the first link component to pivot about its connection to the floor frame and about its connection to the second link component.
There are stop faces on the link components that engage after the first link has pivoted approximately 20.degree.. Thereafter, during a second stage movement, the link components are locked together and upon further pivoting of the first link component about its forward end, the second link component pivots about its rearward end. This dual component link allows the first link to lie at a greater angle (approximately 30.degree.) to horizontal, reducing the initial upward angle of movement of the link, and causes the first stage pivot point to be moved forward (the rear pivot connection of the first link component to the then stationary second link component). Consequently, initial and first stage movement is made easier. The momentum of the first stage movement insures initiation of the second stage.
During the second stage movement, the effective length of the link is increased as the pivot is moved rearward to the point of connection to the seat frame and the effective angle to the link is reduced, thereby increasing the upward angle of movement of the link. The average angle of movement of the pivotal connection at the seat through both stages is approximately 45.degree..
At least initially, the seat back exerts a downward force on the back of the seat because the seat back starts from a rearward inclination. This downward force is promptly followed by an upward force.
In a fifth embodiment the rear connection incorporates a pin on the seat in an arcuate slot in the floor frame. The arcuate slot allows initial movement of the rear of the seat to be forward with a minimum upward component, followed immediately by a continued increasing of this upward component. This action provided by the arcuate slot makes it easier for the rear of the seat to begin its motion against the downward force produced by the seat back. Yet the average angle of movement of the rear of the seat is about 30.degree. to horizontal. The connection at the front of the seat may be the dual component link of the fourth embodiment.
A sixth embodiment of the invention incorporates a pin and slot arrangement at the front and a pin and slot arrangement at the rear of the safety device that is on each side of the seat. Both slots are straight with the front slot being at a greater angle to horizontal than is the rear slot. As illustrated, this angle is 35.degree. at the front and 25.degree. at the rear. Preferably, the slots are supported by the vehicle floor or base frame and the pins are mounted on the seat or seat frame. The slots act as ramps that direct the front and rear portions of the seat in upward motions at controlled angles as the seat moves forward.
A seventh embodiment is similar to the sixth embodiment except that there is a short arcuate path that introduces the pin to the straight portion of each of the front and rear ramps. These short arcuate paths allow the seat to move initially substantially forward with immediately progressively upward components to the motion and to smoothly enter the straight ramp after the seat has gained some momentum. These short arcuate starting slot portions provide greater assurance that the safety device will initiate its action substantially instantaneously upon deceleration of the vehicle.
An eighth embodiment of the invention is a modification of the sixth embodiment and illustrates how the safety device can be constructed to protect a passenger in the event of sudden deceleration in either a forward or rearward direction such as from a front-end collision or a rear-end collision.
A ninth embodiment is similarly a modification of the seventh embodiment to incorporate slot configurations that allow the device to react in response to forward or rearward decelerations.
A tenth embodiment incorporates the concepts of the invention into a chair seat of the kind used for mass transit, such as a bus seat, train seat or an airplane seat. In this tenth embodiment, the rear of the seat swings with pivoting of the rear leg either about a pivot point at floor level or relatively close to floor level. This causes the rear portion of the seat to move upwardly as it moves forwardly. In the illustration of the tenth embodiment, the front of the seat is controlled by a pin and slot arrangement that incorporates a starting arc but it will be understood that other structures may be incorporated for elevating the front as it moves forward.
It will be recognized that while a number of embodiments are described and illustrated herein incorporating means to control movement of the front of the seat and means to control movement of the rear of the seat, still more embodiments can result from various combinations taken from these embodiments. For example, the means to control the front of the seat taken from one embodiment could be combined with the means for controlling the rear of the seat taken from another embodiment.
In all embodiments, because of the difference between the smaller angle at the rear and the larger angle at the front, the initial and continuing rate of elevation of the seat is greater at the front than at the rear. Also, the average rate of elevation at the front is about equal to the average rate of forward movement whereas at the rear, the average rate of elevation is closer to about half the average rate of forward movement.
As has been said, in all embodiments of the invention, it is important that the seat be propelled upwardly as well as forwardly. This happens for different reasons in the embodiments because of the design and because the front and back seats of a vehicle are typically constructed differently. In the front seat construction, the seat back is connected to the seat. In some cases, the seat back is pivotable about connections at its lower end to the seat but is normally latched in a fixed position. In other constructions, the seat back may be tiltable and lockable in a tilted position. In still other constructions, the seat back may be rigidly connected to the seat In all cases, the connection of the seat back is to the seat rather than to the frame of the vehicle.
In contrast, for the back seat and some front seats, the seat back is not connected to the seat because it is bolted directly to the vehicle chassis or to a component that does not move with the seat in response to a collision. As a result, this seat back essentially stops when the vehicle stops because of its firm mounting to the vehicle chassis, whereas the seat back connected to a front seat, which in an at-rest condition is inclined rearwardly, tends to pivot forwardly about its lowermost connections to the front seat. Because the seat back for the front seat starts from a rearwardly inclined position, the applied movement initially has a downward force component as well as a forward force component applied to the rear portion of the seat. This downward force component is immediately followed by and replaced with an upward force component accompanying the forward force component.
As a result of the foregoing, when the vehicle, as by striking an obstruction, is abruptly stopped or slowed down, inertia will cause both the rider and the seat to tend to move forwardly until the deceleration forces are exhausted. Simultaneously, the seat is caused to rise at both the front and rear, the rear rise being less than the front rise because of the shortness of the rear link or the configuration of the rear slot.
One objective is that the safety device initiate movement of the seat at the instant deceleration of the vehicle begins. Another objective is that the safety device maintain the controlled seat movement for the duration of deceleration of the passenger. In addition, it generally appears that increasing the upward angle of movement of the front and/or the rear of the seat improves the effect of the safety device but also deters initiation of such movement. In view of the foregoing, the angles of rise of the front and rear of the seat can vary from those suggested herein. For example, in the embodiment shown in FIGS. 10 and 11, a front angle of about 45.degree. and a rear angle of about 30.degree. have been suggested and in the embodiment shown in FIGS. 21-24 a front angle of 35.degree. and a rear angle of 25.degree. has been suggested, but variations from these suggested angles are possible.